Plasma has been collected from affected patients, quick frozen, and assayed for various catecholamine levels in the search for a specific enzyme abnormality. Double blind crossover drug trials using promising agents such as Dantrolene Sodium (Eaton Laboratories) may be undertaken. Observations in 53 patients with torsion dystonia indicated that the enzyme dopamine beta hydroxylase (DBH), which governs the conversion of dopamine to noradrenalin, is present in abnormally high levels in individuals with the dominant form of torsion dystonia. Serum norepinephrine itself has been determined by a newly developed assay and found greatly elevated in some, but not all, with this form of dystonia.